US2283224A - Projectile - Google Patents

Description

May 19, 1942. I H. .J. NICHOLS PROJECTILE Filed July 6, 1940 materials, parachutes, etc.

Patented May 19, 1942 UNETE azsam AT EN T raomcms Harry I. Nichols, Binghamt'on, N. Y.

Application July 6, 1940, Serial No. 344,261 2 Claims. (01. 102-26) quence, the former simple classification of the projectiles as to types has been greatly extended, and now includes high-capacity, anti-- aircraft, anti-tank, gas, incendiary, smoke, illuminating, tracer, and other specialized types. Many of these specialized types demand the maximum internal capacity for the most efllcient utilization of large bursting charges, chemical Also, gun pressures and projectile velocities have increased, requiring stronger projectiles to withstand the stresses due to firing. In short, the evident trends in special projectile design necessitate optimum design considerations, as well as the extensive use-of high-quality steels.

It should benoted here that the trends described above tend to increase the cost of the individual projectile, both by requiring more expensive, high-quality steels, and by increasing 3 the cost of machining these high-quality steels. The demand for high-quality projectiles in tremendous -quantities also tends to create a milltary-economic problem by reason of the danger of depletion of supplies of strategic materials, such as alloys for special steels, cutting tools, machine tools,- etc. In the World War, the French were forced to thicken the walls of certain projectiles to enable lower grade steels to be used as the supply of alloy steels was depleted, adversely affecting the supply of munitions as well as the performance of the projectiles themselves. The copper used for the rotating bands or projectiles is also a strategic material of prime military importance. Such demands and costs thus become important factors in preserving the military and economical fronts in the event of a long major war.

On studying and analyzing the general and particular considerations touched upon above, I 5 find that important direct and indirect technical, military, and economic advantages can be realized by a radical change and improvement in the form and method of constructing and assembling the rotating bands of projectiles.

i5. a nexed drawings and The rotating band not only forms an essential functional part of all projectiles for rifled cannon, but it also afiects the strength of the projectile, the ballistics of the projectile, and the life, serviceable condition, and accuracy of the gun in which the projectile is fired. It is a reco nized fact of the history of ordnance that the'rotating band of projectiles in its present form is the result of along revolutionary process.

It is accordingly one of the principal objects of this .invention to improve the strength and performance, to facilitate the manufacture, and to reduce the cost of small calibre projectiles by providing a, radical departure in the form of,

and the method of constructing and assembling,

the rotating band therefor.

A further object is to meet in'a highly eflicient, reliable, and practical manner the general and special requirements for the mass productlon of small calibre projectiles for use in rifled guns.

Another object is to improve the strength of the projectile as a whole by eliminating the necessity of cutting a band score in the sidewalls of the projectile.

- Anotherobject is tion of a rotating band on a projectile which eliminates the expense of cutting a groove,-band score, or undercut on the projectile body.

' Another object is to provide'a rotating band on a projectile which eliminates the need for hammering, Dressing, .or squeezing the band into a groove or score in the projectile, which method yet assures a gas-tight connectionbetween the rotating band and the projectile.

Another object is to greatly reduce the quantity of copper needed to form the rotatingband of a tpirojectile, as compared to prior universal prac- Another object is to improve the-rotating band of a projectile with respect to its wearing efiect on the riding of the gun.

Another object is to improve projectiles by providing a rotating band capable of forming a corrosion preventing film on the walls of a gun bore when such projectiles are fired therein.

Another object is to provide a form of rotating Other objects will in part be obvious from the to provide for the construcin part hereinafter indior conical head ll.

cated in connection with the following analysis of the invention.

This invention accordingly consists in the features and forms of construction, combination of parts, and in methods and processes for obtaining unique advantages in the manufacture of projectiles as well as in the projectiles themselves, all as more completely outlined herein.

To enable others skilled in the art fully to comprehend the underlying features of this invention, that they may embody the same in various forms and apply the same to various sizes and types of projectiles as contemplated by the invention, a drawing depicting preferred embodiments of the invention form a part of this disclosure, and in such drawinglike characters of reference denote corresponding parts thruout the several views, in which:

Fig. 1 shows in part section a typical projectile according to the invention and a rotating band applied thereto in accordance with the teaching of the invention.

Fig. 2 similarly shows another embodiment of the invention providing a combination rotating and anti-fouling band applied to a typical form of projectile, all in accordance with the teaching of the invention.

Referring now to the drawing, and particularly to Fig. 1, it is well known that modern projectiles for rifled guns are typically of the same general form, having a cylindrical body III with an ogival The head il may be integral with the body ill, or it may be a separate part, or an assembly of parts- In very small projectiles, a point fuse may serve as a head II, as indicated by the dotted lines of 'the drawing. The forward part of the body I is usually turned or ground to make an accurate cylindrical hearing surface for the front part of the projectile.

- This surface is called the bourrelet and is indi .cated at l2. The body is closed at the base l3,

either by a base plug I l, as in Fig. 1, or by an integrally formed base arch H as in Fig. 2.

The body I0 is also fitted with a driving or rotating band 20. In conventional practice, it is usually located near the base l3 in an annular groove (not shown) machined in and around the body l0. One or more rotating bands may be used, located either closely spaced near the base, or near the base and at the bourrelet. In addi tion, some modern projectiles are fitted with a' creases rapidly as the calibre of the projectile diminishes, and may exceed 40,000 times the weight of the parts forward of a given transverse section in the case of projectiles of small calibre. In fact, in the design of high-capacity projectile I bodies, such as shrapnel shells, (Fig. 2) the separate decoppering or anti-fouling ring in the form of a narrow ring of special non-ferrous metal or alloy assembled to the projectile just rearwardly of the rotating band, or in a groove in the rotating band.

The rotating band 20 performs the functions of centering the projectile accurately and snugly in the bore of the gun, of sealing the projectile in the bore of the gun on firing to prevent the escape of propellant powder gases, and of engaging the rifiing of the gun to impart rotation to the projectile to stabilize the same in flight. In addition to the primary functions of the band itself,

in typical projectiles of the prior art, the effect of cutting the groove for the band, calledthe band-score, into the wallof the projectile body "requires particular consideration from the stand-- point of reducing the ability of the body to withstand the firing forces, and the shock of impact in the case of armor piercing projectiles. view of the importance of these functions, and the need of protecting the bore of the gun against corrosion, wear and damage during the firing of strength reduction of the side wall due to the band-score necessitates the use. of the highest quality alloy steels to withstand the firing forces of modern high'power guns without danger of the body upsetting or collapsing in the bore. At extremely low'temperatures, there is particular danger of damaging or destroying guns due to breaking up of projectiles in the gun because of embrittlement of the projectiles at such temperatures.

The cost of the rotating band itself, the cost of machining the band-score in the body, and the cost of assembling the band. to the projectile comprise a substantial part of the-cost of the complete projectile, particularly in the case of small calibre projectiles. Rotating bands are usually made of copper, or a high-copper alloy such as bronze or cupro-nickel, which must be of high quality and exceptionally uniform in physical properties. According to prior art, the bands are generally made from rings out from annealed, seamless drawn tube of the right size, thickness, and material. The ring is slipped over the projectile to the band groove, and is then hammered or squeezed into place by powerful machinery, not shown. This step of the manufacturing process involves expensive machines or else laborious manual operations, and also presents technical difliculties. The band after being squeezed into place may be strained and loosen up later under further thermal or mechanical strains. Or, due to unequal work hardening during the hammering or squeezing, hard spots may be created which damage the rifiing of the gun at firing. Further, the extensive deformation to which the band is subjected during assembly has in the past closely limited the choice of suitable metals or alloys, since few materials will permit of such extensive deformation as occurs in shrinking a rotating band into place without excessive work-hardening.

In order to prevent the band slipping on the projectile at firing, and to prevent leakage of powder gases between the band and the projectile, special constructions of the band score have been found necessary. One mode of construction widely employed is to under-cut the edges groove are undercut, and pointed ridges in the bottom of the groove are also employed. It will be appreciated'that'while this third mode of construction is quite thorough, it is also very expensive. 1

Referring now again to Fig. 1, according to the methods according to well known practices can be followed to form the rotating band in place on' the projectilebody, the preferred method is that technically known as electro-forming. The following steps (which permit of some vari= ation in order) are preferred: (1) The body itself and the site on the body I!) intended to receive the band isformed or machined to the required size; (2) the body is protected or insulated in such manner as not to receive an elec-' tro-deposit at the time the band is being deposited; ,(3) the site is cleaned and prepared to receive an elctro-deposit thereon in such manner that the deposit will adhere strongly to the body; (4) the body is mounted as a cathode in an electro-plating bath; and by means of electric-current, (5) a metal deposit of the required nature, quality, and thickness is formed as a continuous integral homogeneous ring around the body to the full height of the hand. Thereafter, (6) the perimeter of the band is finish machined to the size and form required. As in the case of present practice, all heat treating processes should ally result in loosening of the band and hence failure to perform the desired functions. A further anti-fouling metals.

be completed before the band is applied. Otherwise, heat strains or annealing effects might cause the band to loosen from the projectile.

Variations in the order of steps recited above are clearly permissible. For example, the entire projectile body may be coated with an impervious coating such as asphaltum varnish, 'or a japan or lacquer, so as to prevent electro-deposits thereon, and thereafter such coating may be removed at the band site when the body is being machinedor ground to size. After suitable preparation, the band is electro-formed in place,

' Regardlem of the order'of steps and the process employed, the invention comprehends preparing the site of the rotating band for depositing metal thereon, insulating other surfaces of the projectile against such deposition, depositing anon-feraas "Electro-depcsition of Metals" by Langbein;

Principles of Electro-plating and Electra-forming by Blum and Hogaboom; and "Modern Elecr -pla ing y 08 3; i 3 However, with respect to the present invention,

it may be pointed out that complete adhesion or bonding between the projectile and electroformed ring is necessary, since because of dissimilar metals being used for the body and band,

Y ing point metallic film as firing progresses. This practical requireme t is that the forming process be closely controlled to assure uniformity in hardness of the deposited metal.

The material deposited to form the rotating band may be a single metal as, for example, pure copper; or a non-ferrous alloy of copper and a dissimilar metal haying anti-fouling characteristics, such as zinc or cadmium; or a ring of copper may be surfaced with a deposit of such dissimilar Because of the facility and speed with which it can be electroformed, copper is the preferred material for the rotating band per se. But to obtain anti-fouling jeifects alloys of, or combinations of dissimilar metals, are requisite. Copper is the preferred material for the rotating band because it can be readily electroplated to build up relatively thick deposits quickly or uniformly.- Any suitable known commercial plating process may be used.

The anti-fouling addition to the rotating band is preferably a superposed layer of metal or alloy electroplated over the copper rotating band after the latter has been machined to size. The term "anti-fouling is intended to cover the prevention or amelioration of various adverse effects of the propellant and projectile on the walls of the gun bore arising from repeated firing. These effects are: corrosive action on the gun bore due to chemical action of the propellant ingredients, gases, and residual compounds; and metal deposits on the gun bore, mainly from the scouring action.

between the gun barrel and the rotating band of the projectile. On repeated firing such metal deposits may, and usually do, accumulate in the bore of the gun tending to impair the accuracy of fire, and unless removed they may cause explosion of the gun or projectile. l

The anti-fouling layer on the. rotating band 1 causes the gun barrel to be coated with a low meltfilm is selflimiting in thickness and inhibits corrosion and copperlng. If ordinarly projectiles having the usual types of copper r'otating bands are fired in the same gun, interspersing projectiles fitted with rotating bands embodying this invention during firing will remove the copper deposits.

formed by such ordinary projectiles. This is an example of de-coppering" action. Referring now to Fig. 2, two featuresare particularly to be noted. The after part of a shrapnel shell of conventional type is shown, witha rotating band according to the invention applied thereto. In shrapnel, it is desired to obtain the maximum capacity within a shell of given size calibre. The strength of the projectile 'side wall at the reduced section when a band score'of OOH-e ventional type is cut therein thus becomes'the limiting factor in the design of shrapnel. It is clear that the present invention provides the advantage of enabling the use of a lower-quality of thermal changes and/or electrolysis may eventusteel for the same thickness of sidewall; provides larger capacity by permitting the use of a thinner side wall while retaining the same quality of steel for the projectile body, provides greater strength of side wall for the same material and thickness. or a combinationof these advantagesin part. 1

Referring "now to the rotating band 20-4: 6r

Fig. 2, the construction there shown represents a laminated or'layer-deposited band in which the layer 20 next to the body may be, for example, pure copper as previously described; while the outer layer, indicated by 2|, is a special anti-- fouling layer, as for example, cadmium or zinc: or alloys containing a high proportion of these metals, as for example an alloy of copper 85-95% zinc -15%- with or without a few percent of cadmium.

In some cases, it may be found desirable to rotate the projectile while depositing the metal of the rotating band. This is especially desirable where the maximum speed in the plating process is desired, and can be advantageously applied to large scale practice of the present invention.

Without further description or analysis, it will readily be perceived that the present invention provides such substantial direct and indirect advantages in the art of construction of projectiles as fairly to mark a revolutionary step in advance. These advantages encompass material advantages in the rotating band per se, as for example, improved mechanical properties such as more uniform hardness, and a wider range in the choice of materials, including alloys having anti-coppering properties; improvement in the functions of the rotating band, as for example stronger adherence to the projectile, stronger grip on the rifiing, and more certain sealing of gun gases; advantages in the design and performance of the projectile, as for example thinner side-walls and larger capacity, greater strength to resist firing stresses, and more uniform flight; and advantages tothe gun, such as diminished wear due to the elimination of hard spots in the bands thus improving the life of the rifling, and by facilitating the use of anticoppering or de-coppering alloys thereby reducing erosion, preserving the accuracy of the gun, and

promoting uniformity in the interior and exterior ballistics.

In addition; the indirect advantages include lower cost of the rotating band; saving in the cost and operation of handing machinery; less copper required; less alloy steel required; less cuttin tools and cutting machines required; etc. In the aggregate, these are substantial advantages, and their attainment by the simple means of the invention represents a distinct advance in the art.

I claim:

' 1. An article of manufacture comprising a ferrous projectile body for rifled cannon having a cylindrical body portionof substantially uniform diameter behind the nose and free from rotating band grooves or lands and having a deposited bonded rotating band in the form of an integral homogeneous ring built up in its entirety directly on the outer cylindrical surface of said body portion to full band height from at least one of the soft non-ferrous metals.

2. An article of manufacture comprising a projectile for rifled cannon having a cylindrical ferv rous body portion of substantially uniform diameter behind the nose and free from rotating band grooves or lands and having a deposited bonded anti-fouling rotating band in integral homogeneous ring form built up in its entirety directly on the outer cylindrical surface of said body portion to full band height, the band comprising copper and at least one anti-fouling metal selected from the group consisting of zinc and cadmium.

HARPY J. NICHOLS.

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